Transcript Ordering a study - NP/CNM/PA Professional Practice Group
Ordering Radiological Exams
Alex Rybkin MD Assistant Clinical Professor of Radiology SFGH/UCSF Nancy Omahen RN MSN NP Referral Coordinator, Radiology SFGH
How to order?
What to order?
(Assumed: imaging is clinically indicated)
Motivation • “I never give accurate history to Radiologists: it biases them and makes me trust them less.”
“Blinded” Radiologist False Negative Rate
37%
For PCP Pneumonia!
Prevalence (Pre-test prob) Radiology Studies PPV, NPV (Post-test prob) Sensitivity: x Specificity: y
PCP Pneumonia Hx: Hypoxia in an AIDS patient with CD4 = 57 Result: PCP Pna Hx: SOB Result: ???
Sens & Spec vary!
(And it’s a good thing) • Clinical situation • Experience • Ability/Training • Adaptation to technique – Techs – Hardware – Display methods
Why Radiologist is not a tool, but a CONSULTANT • Results not binary • Multiple signs and findings • How to combine prevalence info with complex results • Most important: Radiologist has a brain
Don’t Blind Your Radiologist • Think Radiologist as a consultant • Invest time and effort • Help us help you • Summarize signs/symptoms/history – Tell us what you want to know – ICD9 (so we can bill)
Do we need clinical info?
• 2 schools of thought: – Radiologists: We need it, but we are not going to get it – Non-radiologists: They don’t REALLY need it REALITY: Not getting enough specific information
Status Quo • Chest study: “CP”, “SOB” • Abdominal study: “Abdom Pain” • Brain study: “HA”, “Weakness”
Useless
Example of CT e-referral sent by PCP (sent the same information for abd/pelvis CT request) • Diagnostic Question: R/O malignancy • History: Constitutional Symptoms
Useless
• Scrotal Ultrasound: “R/o Hernia” Status Quo
Misleading
Why “Rule Outs” are EVIL • Take us down the wrong path
“R/o Uterine Fibroids vs Enlarged Prostate” Crohn’s disease with “creeping fat” producing a subtle mass
Why “Rule Outs” are EVIL • Take us down the wrong path • Make us second-guess you
R/o Appendicitis
Why “Rule Outs” are EVIL • Take us down the wrong path • Make us second-guess you • Make Radiologists waffle (cannot prove a negative) • Really bad NPV – Limitations of technique (search) – “The hardest thing to find is the one that’s not there”
Why “Rule Outs” are EVIL They will be rejected by billing &
WE DO NOT GET PAID!!
Diagnosis with: • R/O diagnosis • MVA • GSW
Broken lines of communication • Lack of understanding by Providers of what Radiologists need • Roadblocks to info access – Hybrid written/digital ordering – Lack of unified repository of information – Lack of continuity of care Need collaboration within the system!
“But how do I choose the right study?”
Heuristic vs Perscriptive Approach • “Heuristics are rules of thumb, educated guesses, intuitive judgements, or simply common sense” -- Wikipedia • “Heuristics stand for strategies using readily accessible, though loosely applicable, information to control problem solving” – Perl, J et al
Heuristic #1 • If you don’t know how to proceed, don’t guess, ask a Radiologist.
• You can also call the Radiology Nurse Practitioner- x4407
On the Menu: • Plain Films • Fluoroscopy • Ultrasound • CT (Computerized Tomography) • MRI (Magnetic Resonance Imaging) • Nuclear Medicine/PET CT • Angiography
ACR Appropriateness Criteria • acsearch.acr.org
Choosing a study • Comparative studies • Consensus • Usefulness • Do no harm • Availability • Expense – patient – system
Heuristic #2 • Use step-wise approach – Start with inexpensive, less risky studies – Escalate to more advanced studies as needed – No shotgun please!
Imaging Costs (facility fee) • CXR 1 view • Ultrasound abdominal • CT abdomen with contrast • MRI brain with and w/o gad $199 $627 $2279 $7875
Plain Films • Economical • Readily available • Quick • Informative • Good place to start
Chest X-Ray • First-line study of the chest • Varieties: AP, PA & lateral, decubs • PA & lateral: best quality • AP: standby for immobile patients, portable studies • Decubs: eval pleural effusion
Heuristic #3 • Radiological investigation of a Chest problem should always start with a CXR
KUB & Abd series • • • 1.
2.
KUB: supine abdominal film Evaluation for obstruction Abnormal calcifications (kidney stones) 1.
2.
3.
Abd series: KUB, upright chest, +/ decubs Obstruction Calcifications Pneumoperitoneum Further eval: CT
Heuristic #4 • Unless looking for obstruction, don’t bother with KUB
Extremity Films • Good for broken bones, lesions • Very limited Soft Tissue info: effusions, sq emphysema, foreign bodies • For better definition of bone: CT • For better definition of soft tiss: MRI • For foreign bodies: CT or US
Heuristic #5 • Plain films are more valuable than MRI for bone problems!
(Known limitations: osteomyelitis, stress fractures, etc)
General CT considerations • Quick • Available • Relatively Affordable • Problems: – Radiation (children, pregnancy) – Patient Size limit 450 lb – Patient Motion – Pt with ESRD
Radiation Exposure • Up to 2% of cancer estimated due to CT.
– Brenner et al, NEJM 2007
Heuristic #6 • As Low As Reasonably Attainable (ALARA) – US or MRI in children and pregnant women
CT IV Contrast • Benefits: – Better contrast in soft tissues – Better delineation of tissue types – Better sensitivity for tumors/abscesses • Risks – Kidney damage (eGFR < 60) – Allergic reactions – Fluid overload
IV Contrast (cont) • Need eGFR/Cr within 30 days • eGFR < 15 NO CONTRAST • eGFR bet 15 and 60 – Consent – Hydration – Bicarb (Visipaque, N-AC(mucomyst) not effective)
Allergic Reactions • Hx of life-threatening reactions is an absolute contraindication for contrast • Important to know if pt has had prior reaction to intravenous contrast- screen pt for allergies!
• True allergy- anaphylactic (
Type I reactions) or mild (delayed Type 4).
• For mild reactions: premedicate – Call CT for protocol x8069
Head CT • Trauma • Neurosurgical/Neurological Emergencies • For detailed exam: MRI • Contrast: – to better characterize abnormalities seen on noncon – Suspected tumor, abscess etc – HIV
Spine CT • Trauma • Acute Abnormalities • Chronic Abnormalities: MRI • Spine compression: MRI • CT myelogram when MRI not possible
Chest CT • Routine Chest CT: noncon, 2.5 mm cuts, no skips – Good for masses, nodules, effusions – Give contrast for better imaging of mediastinum, pleura • High Res CT (HRCT): noncon, 1mm cuts, 1-2 cm skips – Interstitial lung disease, airways disease – Expiratory images, prone images • PE Protocol CT: with contrast, 1.25 mm cuts, no skips, bases and apices excluded – PE, vascular abnormalities
Abdominal CT • Routine Abd/Pelvis – Most abdominal indications – Oral, +/- Rectal and IV contrast • Renal Stone protocol – noncon, thin cuts • Specialized organ protocols: – talk to you friendly Radiologist
Heuristic #7 • For most abdominal problems requiring imaging, CT is most bang for the buck
Liver studies • Liver Protocol CT: 3 phases – Arterial, Portal, Delayed • Alternative-- US: – less radiation, less sensitivity – useless in proven cirrhosis • Alternative MRI: – better specificity, less availability
Abdom CT: Enteric Contrast • Not absorbed – Minimal risks • Neutral vs Positive contrast – Neutral (hypertonic): better bowel wall definition – Positive: better for perforation, abscess
MSK CT • Exquisite definition of fractures • Usually for preop planning • For most problems rely on plain films and MRI (bone vs soft tissue problems)
Ultrasound • Fast, Cheap, NO RADIATION • Limitations: – Operator dependent – US does not go through bone, air – Labor intensive – Small field of view • Typical indications: RUQ pain, Ob/Gyn imaging, Thyroid, Vascular imaging
Heuristic #8 • US not good for fishing expeditions – Use US for specific indications • If you are going fishing, go with CT
General MRI • Uses High Strength Magnetic fields – No ionizing radiation – Pacemaker absolute contraindication – Metal in body relative contraindication • Better for Soft Tissue imaging • Slow, scheduling difficult, expensive
MRI Contrast • Gadolinium compounds • Used for better ST characterization • Allergic reactions rare • Nephrogenic Systemic Fibrosis (NSF): – Rare, recently discovered – Chronic Renal Failure – Requires consent 15 < eGFR < 30
NSF- nephrogenic systemic fibrosis • • • •
Nephrogenic systemic fibrosis is a rare disease of unknown cause that affects patients with renal failure. Single cases led to the suspicion of a causative role of gadolinium that is used for magnetic resonance imaging.
1.
Marckmann P, Skov L, Rossen K et al (2006) Nephrogenic systemic fibrosis: suspected etiological role of gadodiamide used for contrast-enhanced magnetic resonance imaging. J Am Soc Nephrol 17:2359 –2362 [ PubMed ]
2.
Grobner T (2006) Gadolinium —a specific trigger for the development of nephrogenic fibrosing dermopathy and nephrogenic systemic fibrosis? Nephrol Dial Transplant 21:1104 – 1108 [ PubMed ]
3.
Flaten H (GE Healthcare) (2006) Dear Healthcare Professional. http://www.fda.gov/medwatch/safety/2006/gadolinium_NFD-NSF_dhcp.pdf
. Accessed 07 Sept 2006.
Neuro MRI • Brain: usually second-line study (following abnl CT) • Spine: best for cord, paraspinal pathology, degenerative processes • Needs contrast for tumors, infections
MRA vs CTA MRA – Non invasive eval of arterial system – Images flow, not anatomy-slow flow may mimic stenosis/occlusion – Typical applications: intracranial, neck, renal/mesenteric, peripheral CTA
Heuristic #9 • There are true MRI emergencies – Cord compressions – Posterior fossa infarcts – Appendicitis in pregnant pt
Abdominal MRI • Always second-line study (Except: proven cirrhosis) • Liver: high specificity for HCC • MRCP: Noninvasive Bile/pancreatic duct imaging • Pelvis: GYN pathology characterization, staging of GYN tumors.
MSK MRI • Soft tissue pathology: tendons, ligaments, menisci, capsules, muscles etc.
• Osteomyelitis • MSK Tumor staging (plain films for characterization)
Heuristic #10 • MRI is not part of DJD management – Start with plain films
Osteomyelitis • Plain Film: sens 43-75% spec 75-83% (1) • Triple phase bone scan: sens 94% spec 95%(1) • MRI ROC meta-analysis: superior to bone scan (2) (1) Semin Roentgenol.
(2) Arch Intern Med.
2007 Apr;42(2):92-101.
2007 Jan 22;167(2):125-32.
Conclusion • Don’t Blind your Radiologist • “Rule Outs” are EVIL • Participate! Don’t be discouraged.
Choosing Studies • Don’t guess, ask Radiologist • Use step-wise approach • For chest problems, start with CXR • KUB is for obstruction • For bone problems start with plain films • ALARA • In abdomen CT is most useful • Ultrasound is not for fishing • There are rare MRI emergencies • MRI is not for DJD
Contact numbers Urgent (within 14 days) MRI requests: – NP x4407 Rads (neuro)x5798 Abd Imaging Rads x5898, Musculoskeletal Rads x8030 Urgent (within 14 days) CT requests: -NP x4407 CT chief Tech Kevin x8069 (if unable to reach either of the above, you can contact the numbers above for Rads.
For Scheduling problems: MRI-x 5949 CT, PET CT, US, Nuclear Medicine- Mary Cobbins, Supervisor x5498